1. Field of the Invention
The present invention relates to an icecream-making machine for domestic use wherein a stirring paddle is settled in an icecream-forming container in conditions for thermal exchange with an evaporator coil of a refrigerating system and driven by an electric motor to whip icecream ingredients, and more particularly to an electric control apparatus for automatically stopping the electric motor in the icecream-making machine when the icecream has been completed on its achieving a preferred consistency.
2. Description of the Prior Art
In Japanese Patent Early Publication No. 61-43960, there has been proposed an icecream-making machine wherein the electric current drawn by an electric motor for a stirring paddle is measured to detect a preferred consistency (or viscosity) of icecream formed by rotation of the stirring paddle thereby to automatically stop the electric motor when the measured current has increased up to a preset current value. In Japanese Utility Model Publication No. 56-30222, there has been proposed an icecream-making machine wherein an electric motor for a stirring paddle is stopped when it has been continually supplied with an over-current for a predetermined period of time during preparation of icecream.
If in such convertional icecream-making machines as described above the predetermined current value or period of time is too large or too long, the electric motor will be stopped with a time delay after the icecream has been completed on its achieving a preferred consistency. This results in an increase of electric power consumption and an increase of objectionable stresses acting on the electric motor. Even if the predetermined current value or period of time was selected to stop the electric motor without any time delay after the icecream has been completed on its achieving the preferred consistency, the electric motor would be stopped prematurely due to a difference in characteristics of the electric motor or a difference in commercial frequency of an electric power source. In such a case, the prepared icecream will show poor consistency. In an attempt to solve the problem, it is required to preset the predetermined current value or period of time taking into account of each characteristic of the electric motor and each commercial frequency of the electric power source.